diff --git a/core/js/src/main/scala/vecxt/array.extensions.scala b/core/js/src/main/scala/vecxt/array.extensions.scala
index ec91949..52f9f65 100644
--- a/core/js/src/main/scala/vecxt/array.extensions.scala
+++ b/core/js/src/main/scala/vecxt/array.extensions.scala
@@ -76,7 +76,8 @@ end extension
 
 extension (vec: Float64Array)
 
-  def idxBoolean(index: js.Array[Boolean]) =
+  inline def idxBoolean(index: js.Array[Boolean])(using inline boundsCheck : BoundsCheck) =
+    dimCheck(vec, index)
     val trues = index.countTrue
     val newVec = Float64Array(trues)
     var j = 0
@@ -138,7 +139,8 @@ extension (vec: Float64Array)
     out
   end -
 
-  inline def -=(vec2: Float64Array): Unit =
+  inline def -=(vec2: Float64Array)(using inline boundsCheck : BoundsCheck): Unit =
+    dimCheck(vec, vec2)
     var i = 0
     while i < vec.length do
       vec(i) = vec(i) - vec2(i)
@@ -146,7 +148,8 @@ extension (vec: Float64Array)
     end while
   end -=
 
-  inline def +(vec2: Float64Array) =
+  inline def +(vec2: Float64Array)(using inline boundsCheck : BoundsCheck) =
+    dimCheck(vec, vec2)
     val out = new Array[Double](vec.length)
     var i = 0
     while i < vec.length do
@@ -156,7 +159,8 @@ extension (vec: Float64Array)
     out
   end +
 
-  inline def +=(vec2: Float64Array): Unit =
+  inline def +=(vec2: Float64Array)(using inline boundsCheck : BoundsCheck): Unit =
+    dimCheck(vec, vec2)
     var i = 0
     while i < vec.length do
       vec(i) = vec(i) + vec2(i)
@@ -164,7 +168,7 @@ extension (vec: Float64Array)
     end while
   end +=
 
-  inline def *=(d: Double) =
+  inline def *=(d: Double): Float64Array=
     var i = 0
     while i < vec.length do
       vec(i) = vec(i) * d
@@ -173,7 +177,7 @@ extension (vec: Float64Array)
     vec
   end *=
 
-  inline def *(d: Double) =
+  inline def *(d: Double): Float64Array =
     val out = Float64Array(vec.length)
     var i = 0
     while i < vec.length do
diff --git a/core/js/src/main/scala/vecxt/dimCheck.scala b/core/js/src/main/scala/vecxt/dimCheck.scala
index 2ef742f..c9b5661 100644
--- a/core/js/src/main/scala/vecxt/dimCheck.scala
+++ b/core/js/src/main/scala/vecxt/dimCheck.scala
@@ -17,12 +17,16 @@
 package vecxt
 
 import scala.scalajs.js.typedarray.Float64Array
+import scala.scalajs.js
 
 object dimCheck:
-  inline def apply(a: Float64Array, b : Float64Array) (using inline doCheck: BoundsCheck)=
-      inline if doCheck then
-        if a.length != b.length then throw VectorDimensionMismatch(a.length, b.length)
+  inline def apply[A](a: Float64Array, b: js.Array[A])(using inline doCheck: BoundsCheck) =
+    inline if doCheck then if a.length != b.length then throw VectorDimensionMismatch(a.length, b.length)
 
-case class VectorDimensionMismatch(givenDimension:Int, requiredDimension:Int) extends Exception(
-  s"Expected Vector dimensions to match. First dimension was : $requiredDimension, second was : $givenDimension ."
-)
+  inline def apply(a: Float64Array, b: Float64Array)(using inline doCheck: BoundsCheck) =
+    inline if doCheck then if a.length != b.length then throw VectorDimensionMismatch(a.length, b.length)
+end dimCheck
+case class VectorDimensionMismatch(givenDimension: Int, requiredDimension: Int)
+    extends Exception(
+      s"Expected Vector dimensions to match. First dimension was : $requiredDimension, second was : $givenDimension ."
+    )